Submission #715668

#	Time	Username	Problem	Language	Result	Execution time	Memory
715668		ParsaS	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	619 ms	126676 KiB

tracks

// In the name of God
//        : )
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define mp make_pair
typedef long long ll;
const int N = 4000 + 5;
int di[4] = {1, -1, 0, 0}, dj[4] = {0, 0, 1, -1};
int H, W;
string grid[N];
int dis[N][N];

bool valid(int i, int j) {
    return i >= 0 && j >= 0 && i < H && j < W && grid[i][j] != '.';
}

void solve() {
    cin >> H >> W;
    for (int i = 0; i < H; i++)
        cin >> grid[i];
    memset(dis, 63, sizeof dis);
    dis[0][0] = 0;
    deque<pair<int, int> > dq;
    dq.pb(mp(0, 0));
    int ans = 0;
    while (!dq.empty()) {
        int i = dq.front().fi, j = dq.front().se;
        dq.pop_front();
        ans = dis[i][j] + 1;
        for (int t = 0; t < 4; t++) {
            int x = i + di[t], y = j + dj[t];
            if (valid(x, y) && dis[x][y] > 1e9) {
                if (grid[x][y] == grid[i][j]) {
                    dq.push_front(mp(x, y));
                    dis[x][y] = dis[i][j];
                }
                else {
                    dq.pb(mp(x, y));
                    dis[x][y] = dis[i][j] + 1;
                }
            }
        }
    }
    cout << ans << '\n';
}

int32_t main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    solve();
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70